This invention pertains to the modification of psyllium, and in particular, to the sulfation of psyllium. More specifically, psyllium is a mucilaginous material prepared from the seed husks of the plants of the Plantago genus. The genus including Plantago contains over 200 species, including but not limited to P. ovata and P. psyllium, which are grown commercially in several European countries as well as in parts of Asia including Pakistan and India.
Psyllium possesses many physiological activities such as a hypolipidemic effect, reducing risks associated with colon cancer, reducing hyperglycemia, body weight control, and treatments for irritable bowel syndrome, constipation, and gastric hypoacidity (Arjmandi, et al., (1992) J. Nutr. 122:1559-1565; Allen, et al., (2004) J. Agric. Food Chem. 52:4998-5003). Further research has also discovered that psyllium is useful in drug delivery systems, cosmetic products and the processes associated with water treatment (Baljit, et al., (2007) Carbohydr. Polym. 67:190-200; PCT Application Publication WO2007/087583; Kumar, et al., (2007) J. Appl. Polym. Sci. 103:1025-1034). Of the more than 200 Plantago species, the preferred species is Plantago ovata, which is commercially grown in India. The mucilage polysaccharide of P. ovata is a highly branched acidic arabinoxylan (Yu, et al., (2003) J. Agric. Food Chem. 51:492-495; U.S. Pat. No. 6,248,373). The xylan backbone has both (1→4) and (1→3) linkages. Other monosaccharides present in psyllium include D-rhamnose, D-galactose, D-galacturonic acid, 4-O-methyl-D-glucoronic acid, and 2-O-(2-D-galactopyrano syluronic acid)-L-rhamnose (Chan, et al., (1998) Cereal Foods World 33:919-992).
Notwithstanding all of the health added benefits of psyllium, major challenges still exist in finding effective ways to incorporate psyllium into food and beverage formulas or in dietary supplements and/or other consumer products at the level required for increased health effects. These challenges exist in large part due to the physiochemical properties of psyllium. These physiochemical properties include, but are not limited to, its high viscosity, its strong gelling capacity when placed in aqueous systems, and its strong water absorbing capacity. Due to the strong hydrophilic and gelling properties of psyllium it is difficult to incorporate psyllium in a food or beverage formula because a substantial amount of time is required for complete dispersal and miscibility of psyllium in an aqueous system containing other ingredients, including sugar, even when the aqueous solution is vigorously agitated. An unpleasant slimy mouth feel and undesirable flavor characteristics are also properties associated with psyllium and properties which can be recognized in foods wherein psyllium is an ingredient. Beverages are the preferred carrier of nutraceuticals, however, adding the recommended amount of psyllium into a beverage becomes nearly impossible due to the hydrophilic and gel forming capacity of psyllium.
It is well accepted that the physiological and functional properties of psyllium are highly dependent on their physiochemical properties, which are determined by their molecular and chemical structures. Accordingly, there has been a growing need to provide a method for modifying the physiochemical and functional properties of psyllium such that the less desirable properties of psyllium are diminished and the more desirable effects of psyllium, such as bile acid-binding abilities and other associated health added benefits are simultaneously enhanced. To promote the application of psyllium in foods or other consumer products, it is necessary to improve the functional/biological and physiochemical properties.